The present disclosure relates to a method for the reduction of lung volume.
Chronic obstructive pulmonary disease (COPD) means a wide variety of lung diseases that hinder normal breathing, and is a disease of lung obstruction caused by pulmonary emphysema or chronic bronchitis.
Of these diseases, the pulmonary emphysema refers to a state of abnormal enlargement with destruction of tissues called pulmonary alveolar parenchyma inclusive of respiratory bronchioles, alveolar duct, pulmonary alveoli and alveolar sacs serving as sites of gas exchange. Although the pulmonary alveolar parenchyma in its normal state shrinks at the time of expiration, emphysema-suffering pulmonary alveolar parenchyma does not return into its original state if once enlarged by breathing. Therefore, sufficient breathing is not possible. Moreover, an effective area and vascular bed (blood capillaries running in various directions on the surfaces of the pulmonary alveoli) of the pulmonary alveoli decrease, thereby lowering the ventilatory capacity of the lungs as a whole. In addition, since elastin and the like are destroyed due to inflammation, the elasticity of the lung is lowered and it is not possible to keep stretching and expanding the respiratory tract. The result is a state permitting easy deformation of the bronchi. Accordingly, as the lungs contract at the time of expiration, the bronchi thereof are narrowed by being compressed with the surrounding air-filled pulmonary alveoli, resulting in that the lungs are hyperinflated, making it difficult to release the air.
As a treatment of pulmonary emphysema, at present, lung volume reduction surgery (LVRS) in which the lesion part of the lung is removed so as to promote expansion of normal lung parts is adopted as a surgical method, in addition to the oxygen therapy and pharmacotherapy which alleviate the symptom of the disease on a temporary basis. In the lung volume reduction surgery, however, not only the lesion part of the lung but also much normal part in the vicinity of the lesion part may be removed. In addition, the surgery is highly invasive, and the patient must be kept hospitalized for a long time. Thus, this surgical therapy imposes a great burden on the patient.
On the other hand, Japanese Publication No. JP2012/501813 proposes a therapeutic method for mitigating a hyperinflation state of lung by shrinking the lung, without removing the lesion part of the lung. In this therapeutic method, a shape memory alloy coil having undergone such shaping as to rake up the surrounding tissues is set indwelling in the lung parenchyma such as a bronchus having an emphysema-suffering part, and the tissues in the surroundings of the bronchus are raked up together with the bronchus, thereby shrinking the lung as a whole. Furthermore, by utilizing the elasticity possessed by the coil, tension is imparted to the fiberized lung, so as to assist the shrinkage of the lung at the time of expiration, thereby ensuring easy release of the air from the lung.